Tubing swivels are used in production wells to reduce the effects of erosion at a point of contact between a sucker rod string and an inside surface of a production tubing string. A tubing rotator that is installed at the surface, as part of a wellhead, slowly turns the tubing string from the surface all the way to the tubing swivel installed above the downhole pump. Tubing rotators typically turn the tubing string to the right (right hand rotation).
Depending on the pump being used, the anchoring system that is required, and the specific completion requirements of a particular well, there are three kinds of swivels that can be used: a two way swivel, a one way swivel, and a clutch swivel. The two way swivel is used in applications where Progressive Cavity (PC) pumps are anchored with torque anchors that do not require left hand rotation to be released. The one way swivel is used in applications where PC pumps or piston pumps are used, and they are anchored with torque anchors or right hand set tension and require left hand rotation to be released. The clutch swivel is used in applications where piston pumps are used, and they are anchored with left hand set tension anchors that require right hand rotation to be released.
One common type of clutch swivel is the shear type clutch swivel. U.S. Pat. No. 5,642,782 describes a shear type clutch swivel and U.S. Pat. No. 5,836,396 describes a method of operating a downhole shear type swivel. A disadvantage of shear type clutch swivels is that if the anchor is set in the wrong place or not enough tension can be pulled in the tubing string and the anchor has to be moved, the whole downhole assembly has to be pulled back to surface. The shear clutch swivel has to be re-dressed (the shear pins have to be replaced with new ones), and then the whole assembly is run back into position.
Another disadvantage of existing tubing swivels relates to sealing of swivel components from the production well. In some tubing swivels, components of the swivel are not sealed from the production well, allowing well fluids, sand, etc., to contact the swivel components. Movement of swivel components relative to each other in a sealed swivel tends to create suction, which can similarly pull well fluids and other contaminants into a sealed area of the swivel. Such contaminants can affect operation of tubing swivels.